Study to evaluate the Efficacy of Resin-modified Glass lonomer Cement Liner as a Direct Pulp Capping Material.

AIM: The aim of the present in vivo study was to compare efficacy of light-cured resin-modified glass ionomer liner, Vitrebond™ (3M ESPE) with Dycal® (Dentsply) on the healing of pulpal tissue in the event of a direct iatrogenic pulpal exposure. MATERIALS AND METHODS: Experimental group consisted of Vitrebond™ (3M ESPE) resin-modified glass ionomer liner, and Vitremer™ (3M ESPE) resin-modified glass ionomer cement (GIC) in comparison with the control group of Dycal® (Dentsply) as liner and Poly F® (Dentsply) dental cement. Class V cavities were prepared in 32 sound premolars that were scheduled for orthodontic extraction, and the exposures were capped according to groups. Five teeth from each group were extracted under local anesthesia after an interval of 24 hours, 35 and 60 days, and evaluated for inflammation, fibrotic changes, formation of reparative dentin and bacterial examination. RESULTS: The present study did not show any statistically significant difference between two groups in terms of inflammation, fibrosis, reparative dentin formation, and bacterial examination. CONCLUSION: This study shows that Vitrebond™ (3M ESPE) light-cured resin-modified glass ionomer liner can be used as an alternative to calcium hydroxide as a direct pulp capping material. CLINICAL SIGNIFICANCE: Light-cured resin-modified glass ionomer liner can be an alternative for the calcium hydroxide-based liner for capping iatrogenic pulp exposures.

Does Achievement of Hemostasis After Pulp Exposure Provide an Accurate Assessment of Pulp Inflammation?

PURPOSE: The purpose of this study was to determine in primary molars with carious exposures whether hemostasis at the exposure site and pulp orifice reflected inflammatory status of the pulp at the canal orifice based on cytokine levels. METHODS: Forty mandibular primary molars with deep caries were included in the study. Teeth were divided into two groups: group A had teeth where hemostasis at the exposure site was achieved within five minutes, and group B had teeth where hemostasis at the exposure site could not be achieved within five minutes. Blood samples were harvested from the exposure sites and canal orifices. Cytokine levels for IL-1ß, IL-2, IL-6, IL-8, IL-10, TNF-α, and PGE2 were measured using ELISA for all sample sites. RESULTS: The IL-6 levels at the exposure sites were found to be significantly higher in group A when compared to group B, but there was no statistically significant differences in any of the cytokine levels at the canal orifices between the two groups. CONCLUSIONS: Controlling bleeding at the exposure site or canal orifices does not provide accurate assessment of inflammation at the canal orifice and may be misleading for diagnosing vital pulp treatment in primary teeth with a carious pulp exposure.

Development of a Direct Pulp-capping Model for the Evaluation of Pulpal Wound Healing and Reparative Dentin Formation in Mice.

Dental pulp is a vital organ of a tooth fully protected by enamel and dentin. When the pulp is exposed due to cariogenic or iatrogenic injuries, it is often capped with biocompatible materials in order to expedite pulpal wound healing. The ultimate goal is to regenerate reparative dentin, a physical barrier that functions as a "biological seal" and protects the underlying pulp tissue. Although this direct pulp-capping procedure has long been used in dentistry, the underlying molecular mechanism of pulpal wound healing and reparative dentin formation is still poorly understood. To induce reparative dentin, pulp capping has been performed experimentally in large animals, but less so in mice, presumably due to their small sizes and the ensuing technical difficulties. Here, we present a detailed, step-by-step method of performing a pulp-capping procedure in mice, including the preparation of a Class-I-like cavity, the placement of pulp-capping materials, and the restoration procedure using dental composite. Our pulp-capping mouse model will be instrumental in investigating the fundamental molecular mechanisms of pulpal wound healing in the context of reparative dentin in vivo by enabling the use of transgenic or knockout mice that are widely available in the research community.

Age-related morphological, histological and functional changes in teeth.

Throughout lifetime, the teeth are continuously exposed to numerous chemical and physical impacts, which cause the wear of the dental hard tissues, gingival recession and other oral changes with sometimes subsequent problems. Age-related wear of tooth surfaces reduces the dental enamel thickness and exposes deeper layers of enamel, which have different physical and chemical properties than the surface enamel. Gingival recession is the main causal factor of root caries and dentine hypersensitivity. Age-related changes in dentine include the formation of secondary dentine and the reduction in tubular lumen diameter (dentine sclerosis), which lead to a reduction in the volume of the pulp chamber. In addition to the reduction in the volume of pulp chamber, changes to the dental pulp also include dental pulp calcifications. The age-related physiological changes to the teeth should be carefully distinguished from pathological changes, especially when they induce pain or a negative impact on the oral health-related quality of life (OHRQoL) of the older individuals. Therefore, regular oral examinations coupled with early preventive measures should aim at maintaining oral health until old age.

Behavioral effects of pulp exposure in mice lacking cannabinoid receptor 2.

INTRODUCTION: Cannabinoid receptor 2 (CB2) is an intriguing target for the treatment of pain because of its ability to mediate analgesia without psychoactive effects, but little is known about the role of CB2 in pain of endodontic origin. The purpose of this study was to determine the behavioral effects of dental pulp exposure in wild-type (WT) mice and to explore the contribution of CB2 to these behaviors using CB2 knockout (CB2 KO) mice. METHODS: Pulp exposures were created unilaterally in the maxillary and mandibular first molars of female WT and CB2 KO mice. The open field test was used before pulp exposure or sham surgery, and postoperatively at 1 day, 1 week, 2 weeks, and 3 weeks. Mouse body weight and food consumption were recorded preoperatively and postoperatively at 1 day, 2 days, and 1 week. RESULTS: At baseline, CB2 KO mice weighed significantly more and had significantly greater food intake than WT mice. CB2 KO mice exhibited greater anxiety-like behavior in the baseline open field test, having significantly fewer center crossings and less distance traveled than WT mice. Pulp exposure had relatively little effect on the behavior of WT mice. CB2 KO mice with pulp exposures showed a decrease in food intake and body weight after surgery, and pulp exposure resulted in significantly fewer center crossings in the open field test in CB2 KO mice. CONCLUSIONS: Pulp exposure in CB2 KO mice resulted in behaviors consistent with an increase in pain and/or anxiety.

Involvement of microglial activation in the brainstem in experimental dental injury and inflammation.

OBJECTIVE: The purpose of this study was to determine the effect of dental injury and inflammation on microglia in the trigeminal subnucleus caudalis (Vc). METHODS: Pulp exposure (PX) was performed on the first maxillary molar of 35 rats. Specimens were collected at 1, 3, 7, 14, 21 and 28 days after PX. Teeth were processed for H&E staining and immunohistochemical staining for OX-42, a marker of microgial activation, in the Vc. RESULTS: We observed that there was a progressive and persistent inflammation in the tooth. At 21-28 days after PX, the inflammation extended out into periodontal ligament. Simultaneously, significant microglial activation was observed which starting at 2 weeks and peaking at 4 weeks. CONCLUSION: Dental injury and inflammation induced microglial activation in the Vc. The results indicate that activation of microglia may be implicated in the central mechanisms of pain that can be associated with dental inflammation.

Influence of the degree of dentine mineralization on pulp chamber temperature increase during resin-based composite (RBC) light-activation.

OBJECTIVES: To analyse the influence of the degree of dentine mineralization on the pulp chamber temperature increase during composite light-activation. METHODS: Dentine discs (2mm thick) obtained from recently extracted teeth or those with extensive dentine sclerosis were analysed by FT-IR spectrometry in order to choose the two discs with the greatest difference in the degree of mineralization. A model tooth was set up with the dentine discs between a molar with the pulp chamber exposed and a crown with a standardized class II cavity. A K-type thermocouple was introduced into the molar root until it came into contact with the dentine discs and the cavity was filled with P60 resin composite. The temperature rise was measured for 120s after light-activation began: Standard (S) 600 mW/cm(2)/40s; Ramp (R) 0-->800 mW/cm(2)/10s+800 mW/cm(2)/10s; Boost (B) 85 0mW/cm(2)/10s and LED (L) 1.300 mW/cm(2)/40s (n=10). The same protocol was repeated after grinding the dentine discs to 1.0 and 0.5mm thickness. RESULTS: The temperature increase was significantly higher in dentine with high degree of mineralization (p<0.05). With respect to the dentine thickness, the following result was found: 2mm<1mm<0.5mm (p<0.05). The light-activation mode also presented significant difference as follows: S>R=L>B (p<0.05). CONCLUSIONS: The higher the degree of dentine mineralization the greater the increase in pulp chamber temperature. The temperature increase was influenced by the light-polymerization mode and dentine thickness.

Long term histological response of hemisectioned exposed primary pulps. An in vivo study.

UNLABELLED: THE AIM of this study was to analyze the pulp behavior 17 hemisectioned primary second mandibular molars, exposed into the oral environment. The mesial crown and root portions were extracted after 8 months and analyzed histologically. RESULTS: The cardinal signs such as pain, sensitivity and necrosis were not found in any of these teeth with the exception of one case which had a previous restoration. The formation of pulp polyps, pulp calcifications and pulp obliteration were seen as a normal physio-pathological response. CONCLUSIONS: Exposed pulps, reacted forming pulp polyps and in a similar fashion to exfoliating primary teeth but in an accelerated manner.

The effect of hyperglycemia on pulpal healing in rats.

Diabetes mellitus (DM) may impede healing of dental pulps. In this study, the effect of hyperglycemia on pulpal healing was determined in exposed rat pulps capped with mineral trioxide aggregate. Two groups of 11 rats received injections of saline (control group) or streptozotocin to induce hyperglycemia (DM group). The pulps of the maxillary first molars of all rats were exposed and capped. Intact teeth and teeth with exposed pulps without restorations served as positive and negative controls, respectively. Histologic samples were prepared and evaluated for dentin bridge formation and pulpal inflammation. Data were analyzed by using Fisher exact, Mann-Whitney U, and Spearman correlation tests. Dentin bridge formation was inhibited in diabetic rats (p = 0.029) along with more inflammation in these pulps (p = 0.005). There was an inverse association between dentin bridge formation and inflammatory cell infiltration (p = 0.001). Based on these results, it appears that hyperglycemia adversely affects pulpal healing in rats.

Regenerative potential of dental pulp.

The regenerative potential of dental pulp, particularly in mature teeth, has been considered extremely limited. However, our improved understanding of pulpal inflammation and repair and improved dental materials and technologies make vital pulp therapy a viable alternative to root canal treatment. This article explores our knowledge in this regard and the future potential of saving or even regenerating the pulp as a routine dental procedure.

Regenerative potential of dental pulp.

The regenerative potential of dental pulp, particularly in mature teeth, has been considered extremely limited. However, our improved understanding of pulpal inflammation and repair and improved dental materials and technologies make vital pulp therapy a viable alternative to root canal treatment. This article explores our knowledge in this regard and the future potential of saving or even regenerating the pulp as a routine dental procedure.

Matricellular molecules and odontoblast progenitors as tools for dentin repair and regeneration.

This review summarizes the in vivo experiments carried out by our group after implantation of bioactive molecules (matricellular molecules) into the exposed pulp of the first maxillary molar of the rat or the mandibular incisor of rats and mice. We describe the cascade of recruitment, proliferation and terminal differentiation of cells involved in the formation of reparative dentin. Cloned immortalized odontoblast progenitors were also implanted in the incisors and in vitro studies aimed at revealing the signaling pathways leading from undifferentiated progenitors to fully differentiated polarized cells. Together, these experimental approaches pave the way for controlled dentin regenerative processes and repair.

Reaction of rat pulp tissue to Carisolv 'new gel'--a histocytological evaluation.

BACKGROUND: This study was an histological examination of pulp tissue exposed to Carisolv 'new gel' after 1 to 28 days. METHODS: An occlusal cavity was prepared in 64 caries-free molar teeth of 16 Wistar rats. The roofs of the pulp chambers were perforated and Carisolv 'new gel' solution was placed onto the exposed pulps of 32 molar teeth for 20 minutes. Thirty-two contralateral molar teeth served as controls and were coated with an inert liquid containing isotonic saline solution and carmellose for 20 minutes as well. The pulps of all teeth were capped with Ca(OH)2 and the cavities were filled with a flowable composite in combination with a self-etching dentine adhesive. The animals were sacrificed after 1, 3, 7 and 28 days. Eight teeth per group and the time period were histologically examined, scored, and statistically evaluated (Wilcoxon-test). RESULTS: The results showed no statistically significant differences between the Carisolv group and the control group (p > 0.05). The observed pulp reaction was essentially the same as those reported in the past being typical for the effect of calcium hydroxide as a direct pulp capping agent. CONCLUSION: Compared to Ca(OH)2, Carisolv 'new gel' did not cause any different or additional pulp reaction in healthy teeth.

Effect of Carisolv on the human dental pulp: a histological study.

OBJECTIVES: The aim of this study was to investigate histopathologically after 1 week and 1 month the effect of Carisolv on exposed human pulp after a contact period of 10 min in comparison to sterile saline solution. METHODS: Class V cavities were prepared in 40 human first premolars, and the pulp chambers were perforated. The pulp tissue was either exposed to Carisolv or sterile saline solution for 10 min, covered with Teflon and restored with compomer filling material. After observation periods of 1 week and 1 month, the teeth were extracted and examined by light microscopy. RESULTS: Histological evaluation revealed similar pulpal response which consisted of a slight inflammation in both groups after 1 week. The only difference was localized haemorrhage in controls while no haemorrhage was observed in the test group which may show the haemostatic effect of Carisolv. After 1 month the test teeth displayed a very mild inflammation adjacent to the perforation area while haemorrhage disappeared in the controls. In general, pulps showed structural integrity in both groups. Statistical analysis showed no difference between the test and the control groups in both test periods. CONCLUSIONS: The results suggest that Carisolv is biocompatible with human pulp tissue and may have a haemostatic effect.

Identification of hard tissue after experimental pulp capping using dentin sialoprotein (DSP) as a marker.

The purpose of this study was to identify the hard tissue formed early in experimental pulp exposures capped with mineral trioxide aggregate (MTA) or bone morphogenetic protein (BMP)-7 using dentin sialoprotein (DSP) as a marker. The pulps of 35 maxillary first, second, and third molar teeth from 10 male rats were experimentally exposed. The pulps were capped with MTA alone as a pulp-capping agent and final restoration or with BMP-7 followed by restoration with MTA. Five teeth with class I occlusal preparations, no exposure, and no restoration served as positive controls. Five teeth that received pulp exposures and no restoration served as negative controls. Five untreated third molars served as additional controls. The animals were killed at 2 weeks. The specimens were prepared and evaluated histologically and with immunohistochemistry using polyclonal antibodies raised against rat DSP. Pulps capped with MTA formed hard tissue that demonstrated significantly more immunostaining for DSP compared with BMP-7 (p = 0.0031). MTA-capped pulps also showed significantly more complete bridge formation compared with BMP-7 (p = 0.0008). Pulps capped with BMP-7 demonstrated a hard tissue that was bone-like in appearance and devoid of DSP staining.

Local application of IGF1 on dental pulp mechanically exposed; in vivo study on rabbit.

IGF1 (Insulin Growth Factor, 1) was intentionally applied onto pulp tissues, aiming to provoque a dentine regeneration process through the stimulation of the dentinoblasts' potententials. 72 cavities were hence performed on rabbit molars, intentionally exposing the dental pulp. Different concentrations of IGF1 were then applied; The histo and anatomo-pathological observations showed persistent vitality of the pulp without any sign of necrosis, even 6 weeks after the IGF1 application. Dentinoblasts layers (as an indication of the regeneration activity) were counted, according to a pre-established protocol, at days 7, 14, 22, 28 and 42. The type of the applied IGF1, was carefully selected to be "Binding Protein Resistant" (IGF-BPR), so to avoid any inhibition of the IGF1 action by the endogenous binding proteins (Hochscheid and coll). The results were conclusive in indicating the IGF1 as an efficient dental pulp capping product.

Histomorphometric analysis of odontoblast-like cell numbers and dentine bridge secretory activity following pulp exposure.

AIM: The purpose of this study was to collect quantitative information about the numbers and dentine bridge secretory activity of odontoblast-like cells following dental pulp exposure. METHODOLOGY: The numbers and secretory activity of odontoblast-like cells were measured histomorphometrically between 7 days and 2 years in 161 pulp-exposed nonhuman primate teeth. The area of dentine bridges and the dimensions of cavity preparations were measured. The density of odontoblast-like cells and subjacent reorganizing tissue cells were measured beneath dentine bridge formation. The presence of operative dentine debris and tunnel defects in bridges was noted. Pulp inflammation was categorized according to ISO standards. Bacteria were detected using McKay's stain. RESULTS: The area of dentine bridges was mediated by the density and secretory activity of odontoblast-like cells over time. The cell density of subjacent reorganizing tissue was found to be strongly associated with that of odontoblast-like cells. Bacterial microleakage was found to impede dentine bridge secretion by odontoblast-like cells. CONCLUSIONS: Pulp reparative activity occurs naturally beneath capping materials in the absence of bacterial microleakage. The outcome of pulp-capping treatments could be beneficially influenced by concentrating attention on limiting the width of pulp exposure, minimizing pulp injury by limiting the creation of operative debris and placing materials which prevent bacterial microleakage.

Comparison of pulp responses following restoration of exposed and non-exposed cavities.

OBJECTIVES: The purpose of this study is to compare and contrast differences of pulp responses between non-exposed and exposed cavity preparations in terms of inflammation, frequency of bacterial microleakage, odontoblast and odontoblastoid cell numbers, and tertiary dentine formation. METHODS: Class V non-exposed cavities (n=161) and exposed cavities (n=161 teeth) were prepared in non-human primate teeth. Cavities were restored with calcium hydroxide [Ca(OH)(2)], resin modified glass ionomer, or resin composite. Following extraction (7-730 days), bacteria were detected with McKays stain and pulp reactions were categorized according to ISO guidelines. Teeth were analyzed histomorphometrically and statistically using analysis of variance tests. RESULTS: Exposed cavities in comparison with non-exposed cavities were found to have more severe inflammation (p=0.0001), greater quantities of tertiary dentine (p=0.0001), and an increased frequency of bacterial microleakage (p=0.0034). The density of odontoblastoid cells beneath pulp exposed tertiary dentine was found to be 47.8% of odontoblast cell density beneath non-exposed dentine (p=0.0001). CONCLUSIONS: The restoration of exposed cavity preparations is associated with more traumatic pulp injury and repair responses. Consequently, efforts should be made to minimize iatrogenic dentine removal during cavity preparation and the creation of pulp exposures whenever possible.

The mechanism of pulpal wound healing.

The favourable response of exposed pulp tissue against a variety of materials used for pulp capping in experimental conditions, as observed by hard tissue (reparative dentine) formation, demonstrates an intrinsic capacity of pulp tissue for healing. However, in the clinical situation, in which a pulpal exposure is usually accompanied by a long-term external irritation with the subsequent long-term inflammatory response to that irritation, the outcome of pulp capping procedures is not as predictable. While some of the factors related to the defensive reactions and healing after pulp exposure and capping procedures are well understood, the mechanisms and importance of others remain less well-known. Understanding the mechanisms regulating the spread of inflammation and necrosis in pulp tissue, and the factors regulating healing after closure of the wound, would facilitate the development of new and better treatment procedures with more predictable outcomes. In this review, some of the aspects considered to be important in pulpal wound healing are discussed.

Effect of treatment delay upon pulp and periodontal healing of traumatic dental injuries -- a review article.

Based on an analysis of the literature concerning parameters influencing the prognosis of traumatic dental injuries, few studies were found to have examined possible relationships between treatment delay and pulpal and periodontal ligament healing complications. It has been commonly accepted that all injuries should be treated on an emergency basis, for the comfort of the patient and also to reduce wound healing complications. For practical and especially economic reasons, various approaches can be selected to fulfill such a demand, such as acute treatment (i.e. within a few hours), subacute (i.e. within the first 24 h), and delayed (i.e. after the first 24 h). In this survey the consequences of treatment delay on pulpal and periodontal healing have been analyzed for the various dental trauma groups. Applying such a treatment approach to the various types of injuries, the following treatment guidelines can be recommended, based on our present rather limited knowledge of the effect of treatment delay upon wound healing. Crown and crown/root fractures: Subacute or delayed approach. Root fractures: Acute or subacute approach. Alveolar fractures: Acute approach (evidence however questionable). Concussion and subluxation: Subacute approach. Extrusion and lateral luxation: Acute or subacute approach (evidence however questionable). Intrusion: Subacute approach (evidence however questionable). Avulsion: If the tooth is not replanted at the time of injury, acute approach; otherwise subacute. Primary tooth injury: Subacute approach, unless the primary tooth is displaced into the follicle of the permanent tooth or occlusal problems are present; in the latter instances, an acute approach should be chosen. These treatment guidelines are based on very limited evidence from the literature and should be revised as soon as more evidence about the effect of treatment delay becomes available.